public class Example5_12 {
  public static void main(String args[]) {
    GirlFriend girl = new ChinaGirlFriend();
    Boy boy=new Boy();
    boy.setGirlfriend(girl);
    boy.showGirlFriend();
    girl=new AmericanGirlFriend();
    boy.setGirlfriend(girl);
    boy.showGirlFriend();
  }
}
